James M. Kemper disclosed a filter and pump for a recirculating sanitary system in his U.S. Pat. No. 3,567,032 having a diaphragm pump provided with a coupling to a plurality of needle members reciprocating through an apertured plate, which however has the following drawbacks:
1. If the air flowing through the flexible hose 46 to drive the internal diaphragm 48 is unidirectional and not reciprocative, the filter and pump assembly 30 must be made very large so that the enterred water volume pumped at one time will be enough to flush the toilet. Larger sanitary system is not suitable for a small aircraft or vehicle. If the pneumatic system is reciprocative, the filter and pump unit 30 may then be made smaller, which however may increase the installation cost and maintenance problem of a reciprocating pneumatic system since the reciprocating pneumatic mechanism is always more complex than a simple unidirectional compressed air supply system.
2. The diaphragm may be easily damaged or broken after repeated pumping operations to cause maintenance problems.
3. Even the needle members 80 may serve for expelling particulate matters during the boosting operation sequence. However, when the diaphragm 48 is restored by the return spring 56 to retract the rod member 58, the needle members 80 may also inwardly draft dirts accumulated thereon to possibly clog the apertures 78 and filtering spaces 82, thereby directing the dirts through the apertures 78 into the cup 66, chamber 52 to contaminate or clog other elements of the system. Meanwhile, the whole system is complex in structure and mechanism.
The present inventor has found the drawbacks of the conventional recirculating sanitary system and invented the present simpler recirculating toilet water system.